During the operation, we will encounter constant temperature and humidity test chambers that are not cooled. So, what causes the non-refrigeration? Let us analyze the two factors of non-refrigeration:

One of the two major factors in the constant temperature and humidity test chamber:

Since the temperature of the test chamber can not be maintained, it can be observed that the refrigeration compressor can be started during the operation, and the compressor can be started during the operation of the environmental test equipment, which proves that the electrical circuit from the main power supply to the compressor is normal, and the electrical system has no problem. .

There is no problem with the electrical system, check the cooling system. Firstly, the exhaust and suction pressures of the low-temperature (R23) compressors of the two groups of refrigeration units are lower than the normal value, and the suction pressure is a vacuum state, which proves that the refrigerant capacity of the refrigeration unit is insufficient to exhaust and suck the R23 compressor of the host unit. The air pipe, the exhaust pipe temperature is not high, the suction temperature is not low (no frost), which also indicates that the main unit R23 refrigerant is insufficient.

The two factors of constant temperature and humidity test chamber not cooling:

The cause of the failure was not determined. According to the control process of the experimental box, the cause of the problem was further confirmed. The test chamber required two sets of refrigeration units. One is the host group, and the other auxiliary unit has a large cooling rate. The two units operate at the same time. When the temperature is maintained, the two units are running. When the temperature begins to stabilize, the auxiliary device that stops working is kept stable by the host group. If the host group R23 leaks, the cooling effect of the cooling host group will be small, because during the cooling process, the two units, at the same time, there is no temperature stability, and the cooling rate decreases. During the heat preservation phase, once the auxiliary device stops working, the main unit has no cooling effect, and the test air will rise slowly. When the temperature rises to a certain level, the control system starts the auxiliary device to cool down, and the temperature drops to the set value (55 ° C). Then the auxiliary unit stops working and waits for a malfunction.

So far, the cause of the failure has been confirmed to be the leakage of the low temperature (R23) refrigerant R23 of the host group. For the leakage of the refrigeration system, the inspection method is that the leak detector and the soapy water are combined with each other, and the hot gas bypass valve is found to be cracked by about 1 cm. Replace the solenoid valve, the system is refilled with fluorine, and the system is running normally. As can be seen from the above, the analysis and judgment of the fault phenomenon is mainly from easy to difficult, first "outside" and then "inside", first "electrical" and then "refrigeration" of the vein for analysis and judgment; familiar with the test chamber principle and working process It is the basis of fault analysis.